1. Field of the Invention
The present invention generally relates to pulleys and, more particularly, to braked pulleys used in endless conveyors.
2. Description of Related Art
Braked pulleys are used on endless conveyors to help bring the conveyor to a stop. Braked pulleys are conventionally used on most mining conveyors, such as fixed conveyors and mobile or long-run conveyors, and are necessary on down-hill conveyors. Such braked pulleys conventionally provide a pulley body which is mounted upon a pulley shaft, the pulley body and pulley shaft being joined at ends of the pulley body to force the pulley body to rotate with the pulley shaft. Ends of the pulley shaft project from the pulley body, each end having a brake disc mounted thereon. The brake disc is selectively engaged by brake pads mounted to spring or hydraulically actuated brake calipers and, as such, the overall design of braking assemblies used on conventional endless conveyor braked pulleys generally conforms with the design of disc brakes commonly used in automotive applications.
Such conventional braked pulleys have the braking mechanism exposed to dirty and harsh environments, which tends to limit the useful life of the brake components. Moreover, in applications wherein the conveyor is to be stopped repeatedly, heat generated from frictional engagement between the brake pads and the brake disk has, in the past, caused the braking mechanism to over-heat and fail. As such, regular replacement in high-use applications is common.
The aforementioned conventional braking systems also suffer from structural disadvantages which render their use less than desirable, and has, in some applications, rendered their use impossible. For example, in some fixed conveyor applications, there is limited available space at each end of the conveyor pulley. The conventional design requires the brake discs/calipers to be laterally outboard of the pulley body. As such, inclusion of the aforementioned conventional braking system on some fixed conveyor installations has been problematic, and has resulted in less than optimal installations.
Furthermore, in mobile conveyors, there is not enough space laterally outboard of the pulley body to accommodate the brake discs/calipers. Moreover, in mobile conveyors the conveyor must be stopped often to permit advance/retreat of the conveyor, and the conventional braking system tends to overheat upon repeated use and, therefore, is ill-suited to repeatedly stop the conveyor, as discussed previously. As such, the aforementioned conventional braked pulleys and pulley braking systems are not practically useful in such applications.
Therefore, there exists a need in the art for a braked pulley and a braked pulley system which is dimensionally smaller, and which does not occupy a significant amount of space laterally of the pulley body. There also exists a need in the art for a braked pulley which is useful in installations wherein spacial constraints prevent large exterior braking assemblies from being used. There also exists a need in the art for a braked pulley which is adapted for the harsh and dirty conditions of a mine, and which is adapted for repeated use without overheating.